Sitting before me in a warehouse in an enterprise park in Manchester, incongruously, are two men whose form and fitness could determine whether this sporting summer is a vintage one for these islands. Shane Williams, rugby union superstar, and Andrew Flintoff, cricketing colossus, have never met before, yet there is plenty of common ground. They were born in the same year, 1977, and together they have a chance of making history, or at least of achieving something never done in their lifetimes. Not since 1971 in New Zealand have the British and Irish Lions won a series in the same year that England's cricketers have captured the Ashes, winning what are surely the two supreme battles for sporting supremacy between the British Isles and the old outposts of empire.
First things first, though. To play against Australia, Flintoff must overcome the injury problems that keep surfacing more and more ominously, like the shark in Jaws, and have ruled him out of the current Test series against the West Indies. "I'll be fine," he says, with the weariness of a man used to fielding the same question 37 times a day. "This knee problem had been festering for a while, and I had an operation two weeks ago today, but l'm already off my crutches and I'd love to play in the Twenty20 World Cup. That might be too tight, but I'm in the squad. And the Ashes are ages away."
And what of Williams? With Lions players falling like ninepins, can we at least be sure of the world's greatest winger, as he is widely regarded even outside the Amman Valley, lining up against the Springboks in Durban on 20 June?
"I hope so. I've had my last [pre-tour] game [on Sunday, for Ospreys against Glasgow] and came through that OK, which was a relief. I don't want to jinx myself but I've generally been lucky with injuries, touch wood."
If Flintoff feels an urge to weep with envy at the comparatively unblemished fitness record, in one of the most brutal of contact sports, of an older man (by nine months), he shows no sign. I ask him whether he has ever played rugby?
"I played mini-rugby at primary school. There used to be a tournament at Preston Grasshoppers every year, and our school put a team in. I was quite big for my age, but as everyone else started growing, I didn't fancy it so much then. So my career ended when I was about 11 and from then it was cricket every night of the week. I played a little bit of football, but that was just for acceptance at school. Cricket was seen as a bit... cissy."
Williams's cricketing cv is similarly brief. "I've only played once, for my local pub team, the Cross Keys. I was down as the last to bat and I drank about six cans of lager, then by the time it was my go I think we were all out anyway." Flintoff and I are both too polite to point out that his grasp of cricketing basics seem somewhat shaky. "That," he adds, "was my only taste of cricket. I've also been more of a football or rugby man. And watching it, to be honest I prefer Twenty20."
Flintoff chuckles. "I think everyone does now," he says.
Engagingly, they are both eager to record their admiration for what the other does, and happy to be classed as scaredy cats.
Flintoff: "Having an 18-stone man running at me and I've got to stop him? No. My body falls apart playing cricket. No chance."
Williams: "I'd rather face an 18-stone prop forward than a cricket ball coming at me at 90mph. You can move out of the way of a big guy. You can't always move out of the way of a ball."
The physical challenges might be different, but Flintoff has an idea of what Williams can expect with the Lions in South Africa. "The intensity of the crowd over there takes a bit of getting used to," he says. "At The Wanderers you walk down that tunnel and they're whacking on the side shouting and screaming at you. They're passionate about sport, and they're not shy about letting you know what they think."
Williams agrees. "They hate losing, don't they? I toured there last year with Wales, and it's an intimidating place to play."
Yet the last time the Lions were there, in 1997, the Springboks were defeated, by two Tests to one. Flintoff has watched the video. "It was a different scene in that dressing-room to what I'm used to. There's the odd huddle, and obviously the captain speaks, but there aren't too many slaps in the face, or people throwing up in the corner. On that video I saw Lawrence Dallaglio speaking and it was stirring stuff. You could see from their eyes they were all prepared to run through a wall."
Nonetheless, hasn't Flintoff been known to rouse his team-mates with a bit of Johnny Cash? "Yeah, day five in India, at the end of a series. I put on 'Ring of Fire', and in India there were a few of them knocking about. It turned into a bit of a sing-song, and we went out there and bowled them out. During the 2005 Ashes it was 'Rocket Man' by Elton John all the time. But the team's changed since then. I don't know what they're playing now, probably Dizzee Rascal or 50 Cent or something."
As for the Ashes, I ask Williams whether there is already a buzz in Cardiff, where the first Test begins on 8 July? "There is, yeah. A lot of the rugby boys are looking forward to it. Stephen Jones has been talking about it for months." Sneakily, I then ask him whether there are any particular players he'd like to see taking the field at the Swalec Stadium? He comes clean straight away. "Flintoff and [Kevin] Pietersen are pretty much the only names I know, to be honest."
Flintoff confesses that his knowledge of the likely Lions XV is just as shaky. "But I'd sooner watch rugby than football, even though I don't really understand it." "Neither do I," ventures Williams.
"When Peter Moores was [England] coach," Flintoff continues, "we played touch rugby every morning as a warm up. Some of the lads, like Kevin [Pietersen] and Matthew Prior, who were brought up playing in South Africa, were pretty good. Then there were the duffers like myself and Monty [Panesar]. It was like the schoolyard where you pick a team, and there's always a fat lad left at the end. That was usually me. Even Monty got picked before me. But some of the lads really improved."
"Yes," says Williams. "Some of our boys had a training session with Pietersen, and Gavin Henson said he was quite sharp, really, with the old ball skills."
What, though, when the old ball skills begin to fade in your own sport? How do these two titans cope with loss of form?
"It happens to everyone," Williams says. "You keep working hard, knowing that if you've been that player before, you can be that player again."
Flintoff nods. "For three or four years I had it pretty much all my own way with bat and ball. It's not like that at the moment, but I couldn't be working any harder. The next hundred I score will be the most satisfying ever. But if I didn't think I could perform as well if not better than I have in the past, I wouldn't have had four ankle operations, or had my knee done."
Both men assure me that when they are no longer selected for their countries, they will retire. Williams will not go on playing for the Ospreys, nor Flintoff for Lancashire. But as they push on into their thirties, they both feel better equipped emotionally for the international stage. And what has equipped them, they agree, is fatherhood.
"It's no coincidence that I started playing my best rugby around the time my daughter was born," says Williams. "It took the pressure off. I wasn't constantly thinking about my performances, or what I was going to do in training the next day. It actually helped me to realise that rugby isn't everything; family is. We actually have a little boy on the way in the summer. I'm due back on 7th July, and the baby's due on the 6th, so my wife's not really talking to me at the moment."
In his sport, I say, jerking an impertinent thumb at Flintoff, they come home early.
"Not all of us," says the big man, indignantly. "My middle one, Cory, was born [in 2006] while I was out playing a Test match in Mohali. I'd been asked to captain the team, and I chatted to my missus who said I should stay out. At the time I thought it was the right decision, though maybe not in hindsight. He was three weeks old before I saw him. I'd get pictures of him emailed to me with some of my mates stood there with my boy. But I agree with Shane. Kids put everything in perspective. You come home and they don't know if you've had a good or bad day, which makes it easier to switch off."
Age and experience make it easier, too, they agree, to cope with the opinions of former players working as pundits. "That's not something I could see myself doing," says Flintoff. "All that travelling without the thrill of playing? That's not for me. I have no qualms with them criticising a performance, but there's a fine line between that and criticising a man's character. That used to get to me, but not so much now."
"Me too," says Williams. "I used to hold grudges, but now I laugh it off."
And have the two recent Grand Slams put to bed the obsession with Welsh rugby's halcyon 1970s? He smiles. "No. The 1970s will never be put to bed. Our Grand Slams are mentioned occasionally, but the '70s are still like a religion in Wales, with Gareth Edwards as a god. I was brought up with that, though. Gerald Davies was one of my heroes. I can live with it."
And what about Flintoff? At least his team's feats in 2005 ended all the nostalgia for 1981, and Botham's Ashes. "Yes," he says, "but now we have to move on from 2005." Bullseye, just to bring a third sport into the equation.
Shane Williams and Andrew Flintoff were speaking at a Puma photo shoot; www.puma.com